In recent years, color images have become popular, and a demand for high resolution has been increasing. In digital full color copiers and printers, an original color image is subjected to color separation with filters of blue, green, and red, and then a latent image corresponding to the original image is developed using developers of yellow, magenta, cyan, and black. Therefore, the tinting strength of each colorant contained in the developer of each color highly affects the image quality.
In addition, the reproducibility in color space, such as the Japan Color standard in the printing industry and Adobe RGB in the Desk Top Publishing (DTP), is an important factor. In the reproducibility of color space, it is known to improve the dispersibility of pigment or to use a dye having a broad color gamut.
As examples of yellow colorants for toner, compounds having an isoindolinone, quinophthalone, anthraquinone, or azo skeleton are known. Although these compounds are widely used as pigments, they have limitations in transparency and tinting strength, which are improved by using dyes. For example, a pyridoneazo compound (monomer) having one azo bond is known as a yellow colorant (see PTLs 1 and 2).
However, a dye having further excellent saturation and light resistance is demanded to be developed for improving image quality.